Antigenic and biological characterisation of avian paramyxovirus type I isolates from pigeons - an international collaborative study

During 1981-1983 a disease of pigeons (Columba livia), characterised predominantly by nervous signs, spread across Europe. In the present study 57 viruses isolated from pigeons from 15 countries (12 European, Japan, Israel and Sudan) were characterised. All were shown to be avian paramyxoviruses of the A/PMV-1 serotype. Monoclonal antibody binding tests showed 53 of the viruses to be identical. The virus from Sudan was similar to these viruses but showed distinguishable variation. One vaccinal virus from France and two virulent viruses from Czechoslovakia were unrelated to the other pigeon A/PMV-1 isolates.     

Characterization of Newcastle disease virus isolates obtained from Eurasian collared doves (Streptopelia decaocto) in Italy

Eurasian collared doves (Streptopelia decaocto) are thought to originate from India and they have colonized, throughout the centuries, the Middle East and, more recently, Mediterranean countries such as Italy and Spain. In the present paper we report of the isolation and characterization of Newcastle disease viruses (NDV) obtained from Eurasian collared doves during 2000-2001, and compare them to isolates obtained from feral pigeons (Columba livia) during the same period. All isolates could be classified as avian paramyxovirus type 1 (APMV1) and belonged to the pigeon variant group (PPMV1), as their haemagglutinating activity was inhibited by mAb 161/617 which is specific for PPMV1. The intracerebral pathogenicity indices ranged from 0.68 to 1.38 and all isolates contained multiple basic amino acids at the deduced cleavage site of the fusion protein, which is a typical feature of virulent viruses. Phylogenetic analysis of the isolates indicate that 18/20 of these form a separate cluster from the isolates obtained from pigeons in the same period. These findings suggest that different lineages are circulating in feral pigeon populations, and that a separate lineage affects Eurasian collared doves.     

The first isolation of the avian pmv‐1 virus responsible for the current panzootic in pigeons ?

From a virus stock (designated BVC 78) of 'viral encephalomyelitis of pigeons' an avian paramyxovirus type 1 was isolated in 1981. This virus shares all known characteristics with paramyxoviruses which were later (1982/84) obtained from diseased pigeons in the panzootic in Europe and elsewhere. It appears that the BVC 78 virus represents the first isolate of the pigeon PMV-1 viruses.     

Isolation of an antigenically unusual paramyxovirus type 1 from chickens

An antigenically unusual paramyxovirus type 1, designated PMV-1/ chicken/Ulster/Espey/86, was isolated from 22-week-old broiler breeders. Using cross-haemagglutination inhibition tests, this virus showed a predominantly one-way cross with the Ulster 2C strain of Newcastle disease virus (NDV). Antisera to NDV had similar titres to Ulster 2C NDV and to PMV-1/Espey, but convalescent antisera to PMV-1/ Espey had substantially lower titres to NDV than to the homologous vims. These low antibody titres could in some circumstances be ignored or misinterpreted as being non-specific, particularly as PMV-1/Espey was shown to be avirulent for chickens.     

Antigenic variation in avian Paramyxovirus type 3 isolates detected by mouse monoclonal antibodies

Six mouse monoclonal antibodies raised against PMV-3/turkey/England/ MPH/81 were used to assess relationships between PMV-3 viruses isolated from exotic birds and from domestic turkeys. Twelve PMV-3 isolates from birds held in quarantine in Great Britain and nine isolates from exotic birds in Netherlands, USA, Belgium, France and F.R. Germany were inhibited by only one monoclonal antibody, 50/1412, in haemagglutination inhibition tests. In contrast PMV-3 isolates from turkeys in England and France were inhibited to high titres by all six monoclonal antibodies. Two isolates from North American turkeys and one from a turkey poult in the Federal Republic of Germany were inhibited only by monoclonal antibody 50/1412 and, to low titres, by one other monoclonal antibody. Monoclonal antibody, 50/1412, showed no inhibition of 12 varied PMV-1 strains or representatives of other avian paramyxovirus sero-types and may be useful in the differential diagnosis of PMV-3 viruses.     

Quantitative estimation of Newcastle disease virus antibody levels in chickens and turkeys by ELISA

A quantitative single-well ELISA for estimation of Newcastle disease (ND) virus antibodies in chickens and turkeys was developed using purified antigen from PMV-1/Chicken/Ulster 2C/71. The test was standardised using sera from 20-week-old chickens or 20- 30-week-old turkeys. Absorbance values for negative sera in chickens increased with the age of the birds but overall was lower than the cut-off for the test. ND haemagglutination inhibition (HI) positive field sera were always positive by ELISA and the mean was significantly higher than that of the negative population. Standard antisera to four of seven of the other PMV serotypes (including PMV-3) gave positive reactions in ELISA and three were also positive at low level by PMV-1 HI test. Absorbance values remained negative in turkeys given two inoculations of PMV-3 vaccine in spite of good PMV-3 HI responses. Doubling dilutions of chicken and turkey sera were tested by ELISA and end-point titres calculated. Standard curves relating ELISA titre and absorbance of each sample at 1/100 dilution were constructed and used to determine titres of test samples from single well absorbance values. A significant positive correlation between ELISA titre and HI titre for chicken and turkey sera was demonstrated. Sensitivity of the test was investigated using birds experimentally infected with PMV-1/Chicken/Ulster 2C/71 or a pigeon PMV-1 isolate. Seroconversion was detected at the same time by ELISA and HI. In experiments to estimate the ELISA titre required to protect birds against virulent ND, five groups of chickens were vaccinated twice with one of four commercial ND vaccines (three inactivated; one live) on two occasions and challenged with a virulent ND strain (PMV-1/ Chicken/Antrim/73). Two of the groups vaccinated with inactivated vaccines were protected against challenge. In another group also given inactivated vaccine, clinical signs were seen in one bird and ELISA proved a better indicator of immune status than HI. In the groups given living vaccine, no signs of ND were seen and ELISA indicated a much higher level of vaccinal antibody than HI test. In turkeys given two inoculations with inactivated vaccine, antibody levels were boosted to acceptable levels by ELISA and HI indicating that vaccinal antibody levels were adequate.     

Matrix Protein Gene Sequence Analysis of Avian Paramyxovirus 1 Isolates Obtained from Pigeons

The matrix protein gene was cloned and sequenced for several recent isolates of avian paramyxovirus type 1 (APMV-1). Specifically, isolates from pigeons and doves, members of the Columbidae family were examined. APMV-1 is the causative agent of Newcastle disease and the virus is associated with disease among a diverse number of avian species. Newcastle disease virus (NDV) isolates from pigeons have also been classified as pigeon paramyxovirus type 1 (PPMV-1). Matrix protein gene sequences for PPMV-1 isolates clustered together as a group relative to isolates from other species phylogenetically. However, there were also isolates from pigeons or doves that grouped with APMV-1 isolates from other species. This indicates that PPMV-1 may be circulating among Columbidae members as a distinct lineage, but that these avian species may also harbor other NDV strains as well. Of particular interest was a dove isolate from Europe that had an aberrant fusion protein cleavage site and was an outlying member phylogenetically between the two major groups of APMV-1 isolates.     

Fusion and Matrix Protein Gene Sequence Analysis of Paramyxoviruses of Type 1(PMV-1) Isolated from Pigeons in Slovenia

Paramyxoviruses of type 1 (PMV-l) isolated from pigeons were genetically analyzed. A part of the fusion and the matrix protein genes were amplified and sequenced, Typical amino acid sequences associated with virulence were determined at the fusion protein cleavage site in all PMV-1 isolates. All Slovene pigeon PMV-1 strains share high amino acid sequence similarity with other pigeon strains. In the phylogenetic tree, they are clustered together with pigeon PMV-1 isolates with moderate pathogenicity. Phylogenetic analysis obtained from the fusion and the matrix protein gene alignments showed the same branching order. Viruses circulating among pigeons were found to form quite unique lineage of virulent NDV strains.     

Characterization of avian paramyxovirus type 1 strains isolated in Germany during 1992 to 1996.

In Germany all avian paramyxoviruses (APMV) isolated in regional laboratories are collected and characterized by the National Reference Laboratory. From 1992 until 1996, 635 APMV-1 virus isolates were submitted from almost all regions. Of these viruses, 371 were isolated from chickens, 39 from other poultry, 171 from pigeons and 54 from exotic birds. All isolates were examined for virulence in intracerebral pathogenicity index (ICPI) tests, for their ability to react with a panel of monoclonal antibodies (mAb) and their thermostability. In addition, the nucleotide sequences of the cleavage site of the fusion protein of a few virus isolates were determined. Most isolates from chickens and other poultry were of the velogenic pathotype. This virus was responsible for the epizootic in 1993 to 1995 in many small flocks. The same virus was obtained from some pigeons and some exotic birds. The pathogenicity of the velogenic/epizootic virus was high with most viruses giving ICPI values of 1.8 to 1.9, and the sequences of the cleavage site of all velogenic isolates tested were closely related. However, viruses isolated at the beginning of the epizootic period differed from viruses isolated towards the end in their reaction with some mAbs. 149 virus isolates were identified as pigeon variant PMV-1 (PPMV-1). Most of these were obtained from pigeons but a few were isolated from chickens and other birds. Most lentogenic isolates proved to be vaccine virus strains.     

A comparative infection study of pigeon and avian paramyxovirus type 1 viruses in pigeons: evaluation of clinical signs,virus shedding and seroconversion

The pathogenesis of pigeon paramyxovirus type 1 (PPMV-1) isolate AV324/96 and of its recombinant derivative, rgAV324, was studied in pigeons. For comparison, the virulent chicken virus FL-Herts, which is a recombinant derivative of strain Herts/33, was also included. After inoculation by the combined intraocular, intranasal and intratracheal route, clinical signs, virus shedding and serological responses were examined. Clinical signs were observed only in the FL-Herts-infected group. All virus-inoculated pigeons had positive tracheal swabs until 5 days post infection. However, only the AV324/96-infected and rgAV324-infected birds, and not the FL-Herts-infected birds, shed virus in the cloaca. The AV324/96-infected pigeons showed higher mean antibody titres than the rgAV324-infected birds, whereas the antibody titres of the FL-Herts-infected group were rather low. The results show that the pigeon strain AV324 is not virulent for pigeons, but underlines the potential risk of poultry becoming infected by PPMV-1 shed by non-symptomatic pigeons.     

Evaluation of relationships between avian paramyxoviruses isolated from birds of the familyColumbidae

Summary The prototype virus for the PMV-7 serotype of avian paramyxoviruses, PMV-7/dove/Tennessee/4/75 (Tn/4) and five other isolates obtained from birds of the Columbidae family, which had been shown to be distinct from PMV-1 serotype, were tested for antigenic relationships between themselves and to other avian paramyxoviruses. By serological tests and analysis of structural polypeptides the viruses appeared to be distinct from other avian paramyxoviruses. One isolate appeared to be very closely related to Tn/4. Three other isolates showed only minor relationships to these two but were very closely related to each other. However, the sixth virus, pigeon/Japan/Otaru/76, showed high levels of homology in haemagglutination inhibition tests and at least one line of identity in immunodoublediffusion tests with all five of the other isolates.     

Antigenic and biological characterization of avian paramyxovirus type 1 isolates from pigeons

Summary 21 A/PMV-1 viruses were isolated from pigeons and characterized using polyclonal and monoclonal antisera in hemagglutination inhibition, sero-neutralization and immunoprecipitation studies.Polyclonal and monoclonal antibodies directed against the HN and F proteins of Italien virus reacted with all pigeon isolates showing a close relationship between chicken velogenic and pigeon viruses. Differences in the M.W. of F₀, P and M proteins were however observed between pigeon and chicken Italien virus.Marked differences in virulence were recorded among pigeon isolates; these were reflected by great variation in the IVPI of the different strains.With 3 Figures     

Avian paramyxoviruses of PMV-3 serotype in British turkeys

Serological testing of turkey flocks in Great Britain was undertaken as a result of the isolation of an avian paramyxovirus of serotype PMV-3 from turkeys in 1981 (Macpherson et al., 1983). Turkeys on two of four farms with egg production problems examined for PMV-3 haemagglutination inhibition (HI) antibodies in 1981 were positive. Turkeys on 34 farms were tested for PMV-3 antibodies in 1982. Seven of 16 flocks showing egg production problems and/or respiratory disease were considered positive for PMV-3 (mean log(2) HI titre >/= 2.5), but five of 18 flocks with no reported disease were also positive for PMV-3 antibodies. On one turkey farm the appearance of PMV-3 antibodies and an isolation of a PMV-3 virus coincided with egg production problems. Analysis of HI titres in turkeys vaccinated against Newcastle disease virus (NDV) and unvaccinated birds suggested that significant NDV HI titres are unlikely to be recorded as a result of PMV-3 virus infections of unvaccinated birds. However, while NDV vaccination prior to PMV-3 infection apparently caused slight suppression of the PMV-3 immune response, the HI titres to NDV were boosted considerably in direct relationship to the PMV-3 titre.     

Characterization of viruses from doves representing a new serotype of avian paramyxoviruses

Summary Five viruses isolated from 114 hunter-killed doves (Columba species) in Tennessee, U.S.A. in 1975 were shown to be related paramyxoviruses which represent a new serologically distinct group of avian paramyxoviruses. We propose that this subtype be designated as PMV-7 in the current system of nomenclature.With 1 Figure     

Characterization of paramyxoviruses isolated from penguins in Antarctica and sub-Antarctica during 1976–1979

Summary Nine paramyxovirus isolates obtained from penguins were tested for antigenic relationships amongst themselves and to other avian paramyxoviruses. One of the isolates was shown to be a lentogenic Newcastle disease virus (NDV), i.e., of PMV-1 serotype. By serological tests and analysis of structural polypeptides the other penguin isolates could be placed into three groups. No relationship with other avian paramyxoviruses could be determined except that six of the penguin viruses, representing two of the groups, showed reaction with a monoclonal antibody raised against NDV Ulster 2 C and three of the isolates, representing one of the penguin groups, also reacted with another PMV-1 directed monoclonal antibody.     

Persistent West Nile virus transmission and the apparent displacement St. Louis encephalitis virus in southeastern California, 2003-2006

West Nile virus (family Flaviviridae, genus Flavivirus, WNV) invaded the Colorado Desert biome of southern California during summer 2003 and seemed to displace previously endemic St. Louis encephalitis virus (family Flaviviridae, genus Flavivirus, SLEV, an antigenically similar Flavivirus in the Japanese encephalitis virus serocomplex). Western equine encephalomyelitis virus (family Togaviridae, genus Alphavirus, WEEV), an antigenically distinct Alphavirus, was detected during 2005 and 2006, indicating that conditions were suitable for encephalitis virus introduction and detection. Cross-protective "avian herd immunity" due to WNV infection possibly may have prevented SLEV reintroduction and/or amplification to detectable levels. During 2003-2006, WNV was consistently active at wetlands and agricultural habitats surrounding the Salton Sea where Culex tarsalis Coquillett served as the primary enzootic maintenance and amplification vector. Based on published laboratory infection studies and the current seroprevalence estimates, house sparrows, house finches, and several Ardeidae may have been important avian amplifying hosts in this region. Transmission efficiency may have been dampened by high infection rates in incompetent avian hosts, including Gamble's quail, mourning doves, common ground doves, and domestic pigeons. Early season WNV amplification and dispersal from North Shore in the southeastern portion of the Coachella Valley resulted in sporadic WNV incursions into the urbanized Upper Valley near Palm Springs, where Culex pipiens quinquefasciatus Say was the primary enzootic and bridge vector. Although relatively few human cases were detected during the 2003-2006 period, all were concentrated in the Upper Valley and were associated with high human population density and WNV infection in peridomestic populations of Cx. p. quinquefasciatus. Intensive early mosquito control during 2006 seemed to interrupt and delay transmission, perhaps setting the stage for the future reintroduction of SLEV.     

Pigeons are resistant to experimental infection with H7N9 avian influenza virus

To determine the susceptibility of pigeons to the newly emerged avian influenza virus subtype H7N9, we experimentally infected three different types of pigeons (meat, town, and racing) with two different doses (2?×?10⁴ or 2?×?10⁵ EID₅₀) of H7N9 avian influenza virus A/Chicken/China/2013 by either intranasal and intraocular inoculation (IN?+?IO) or intravenous injection (IV). In addition, the potential transmission of H7N9 to pigeons by direct close contact with experimentally infected pigeons and chickens was assessed. Results showed that none of the experimentally infected pigeons exhibited any clinical signs regardless of the infection route and dose. Of the 12 racing pigeons that were randomly selected and necropsied, none of them had any gross lesions. In agreement with this finding, virus was not isolated from all pigeons. No detectable H7-specific antibodies were found in any pigeon. In contrast, 11 of 31 chickens that were either directly infected with H7N9 by IN?+?IO inoculation or by contact with IN?+?IO-infected chickens had conjunctivitis. Virus was isolated from all 31 chickens and H7-specific antibodies were detected in these chickens. However, none of the IV-infected chickens or chickens in direct contact with IV-infected chickens had any clinical signs. No virus was isolated from these chickens and no H7-specific antibody was detected. Overall, we conclude that pigeons are less or not susceptible to the H7N9 virus at the doses used and are not likely to serve as a reservoir for the virus. However, the virus does cause conjunctivitis in chickens and can transmit to susceptible hosts by direct contact.     

Isolation of mycoplasma spp. from racing pigeons (Columba livia)

Live and dead racing pigeons (Columba livia) from five lofts in Norfolk and Suffolk were examined clinically and cultured for Mycoplasma spp. Both clinically healthy birds and those showing signs of mild respiratory disease were included. The oropharynx was the culture site for 130 live birds, the nasal sinuses and other tissues for 58 carcases. Mycoplasma columbinum, M. columborale and M. columbinasale were isolated from the oropharynges and nasal sinuses; M. columbinum and M. columbinasale from the brain and M. columbinum and M. columborale from lungs and air sacs. One or more of these three Mycoplasma spp. was isolated at necropsy from 28% of 58 pigeons. Only 11% of 37 pigeons reacted sero-logically by the metabolism inhibition test to M. columbinum and none to M. columborale. Twenty-five birds examined for M. gallisepticum antibody by the haemagglutination-inhibition test were negative. No sex or age predilection to infection with Mycoplasma was apparent. About 10% of pigeons in all five lofts showed clinical signs of the respiratory disease sometimes described as 'mycoplasmosis catarrh', but most dead birds from which Mycoplasma spp. were isolated also had concomitant infections of various kinds. Although suggestive, the results of these investigations provide no clear evidence that Mycoplasma spp. are aetiologically involved in natural respiratory disease of pigeons. No conclusive satisfactory treatment was found for the elimination of mycoplasmas.